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Found 39 results

  1. If backbone is poly, attributes come across to geometry created by sweep If they are nurb, resulting geometry gets '0'.. wondering if that's a bug, or expected.. thanks Alex help doesnt mention backbone nurb vs poly.. These point attributes and groups will be copied from the backbone points to the cross-section points. If a uv attribute is present on both the cross-section and backbone, and Cycle Type is set to either One Primitive at a Time or Cycle Primitives, only the u component will be copied from the backbone, so the v component will still be from the cross-section uv attribute. Although only point attributes are copied from the backbone, there is a special case for if the cross-section has a vertex uv attribute, point uv values can be copied into the destination vertex uv attribute, but this only works for uv.
  2. I feel like Houdini must be able to do this, but I can't figure it out... I want to take a vector point attribute and write it out to a 16-bit image file. So for example, for point 0, my attribute @out_P has a value of {561.0, 981.0 ,1174.0 }. I want to create an image sized 256x256 pixels and write the first pixel value to be this value of @out_P. Second pixel is the @out_P value of point 1, and so on... How would I go about doing this?
  3. hi there, I have a global attribute that i've made in a python node: citySearcherDistanceTrav = geo.addAttrib(hou.attribType.Global, 'citySearcherDistanceTrav', '') i've then set the attribute with some floats totalDistance = self.stepSize * hou.frame() #speed * time = distance travelled dt = str(totalDistance) geo.setGlobalAttribValue('citySearcherDistanceTrav',dt) #see image 1 But i can't seem to access the values in the next node directly below. I tried find global attrib not sure how to access the data in a python node again. A
  4. Hi, I've tried it over and over. Suddenly the complete attributes are missing in the POP. I dont know the concrete circumstances when it happens. I think its different. Is it my fault, missing something, a bug? disintegration_v.2.hip
  5. Hi, I've tried it over and over. Suddenly the complete attributes are missing in the POP. I dont know the concrete circumstances when it happens. I think its different.
  6. Hi, I've tried it over and over. Suddenly the complete attributes are missing in the POP. I dont know the concrete circumstances when it happens. I think its different. disintegration_v.2.hip
  7. Hello, one question please: What expression can I write to use the @ptnum attribute to drive the @P.y attribute using VEX or Python expressions. What if I want to drive @P.y with @P.x ?? thanks in advance.......
  8. use of Energy Attribute - FEM

    Hey guys, About this energy attribute, I think I could make a good use of it but I don't know how to access it. I mean, I can see it in the dops geometry spreadsheet but it doesn't get out there. I can't see it in sops. My main doubts are: - Can I bring this attributes to sops? (dissipationdensity, kineticdensity, potentialdensity) - Can I use it in dops? (use it as a multiplier for some other parameter, like the fracture threshold for example) Thank you fem.energy.v1a.rar
  9. Hi there, I am trying to build a propagation driven blend / morph effect to change the look of a geometry. But I am already stuck by transfering the atrributes between the geo A and geo B. I managed to build a set up where I change the geometry by using a attribute vop and subtracting B minus A. Here come the BUTs couldn´t animate it by keyframing the Bias of a mix node. couldn´t use a propagation effect with scattert points In the second set up I tried to change the set up by using a scatter node insted of the normal geometry. It works but it seems that the point order isn´t the same and while changing the bias of the mix node all the points change it´s position?! In the scatter node I unchecked "Rondomize Point Order" but without any effect. I also tried to use set up with the change from lowres mesh to a highres mesh, but here I couldn´t get solution with the scattered point, because of the primitive Attribute node in the second Vop. I also tried to recreate it with point cloud node but failed as always. I am pretty new to Houdini and I know that I am missing a lot of foundation knowledge, it would be great if someone could give me a hint what I am doing wrong. Thanks and all the best Dennis 170422_position_transfer_001.hiplc
  10. Deleting wet attribute

    Hi, probably a simple one but I'm having problems deleting points based on a point attribute called "wet". So its a wet map. The delete sop isn't willing to delete anything here. Any hint? Thanks
  11. Group Attribute

    Looking at the Geometry Spreadsheet. A Group SOP creates an attribute like "group:foo": I can easily access that group "attribute" in a Wrangle like so: i@myvalue = @group_foo; QUESTION: How do I access that group attribute on parameters that requires an attribute name? For example, in a Color SOP's Random from Attribute: Or on a Delete SOP's Filter Expression: Although I know that I could just type the group name on the group field. I'm just curious if there's a way to access the Groups data as "Attributes". Particularly, I'm asking because I want to access Groups as an "Attribute" in the Enable Solver DOP without actually creating an actual attribute to represent the group: Hopefully I'm just missing or forgetting the proper syntax.. P.S. The Enable Solver could use an option where it can check for existing groups. I'll probably send an RFE
  12. POPS

    Hi all, I am trying to use geometry to control attributes on particles. Would anyone know how to do that? Problem. I have a flat bed of sand grains with their "static Kinetic" set very high. But I would like the collision geometry (a hand in this case) to diminish the "static Kinetic" attribute to a very low setting. Much like using the sop solver for fluids. Cheers, dreamagery
  13. Temporary variables in VEX Help

    Hi I'm new to this wrangle node programming, I've been busting my head over why this doesn't work for three days, it's so simple therefor i must be missing out on some general vex concepts. If anyone can please point me in the right direction that would be greatly appritiated. I have a bunch of points on a grid and their moving up and down via noise. I am trying to set up a point attribute that has a value of 1 when a point if moving up (positivly in the Y axis) and a value of 0 when a point is moving down (negativly in the Y axis). This attribute is called Direction, I'm computing the logic on temporary VEX variables and then writing them out to the attributes. Here's how it looks like : // 0 is going down, 1 is going up, -1 means the point has no direction // on the first frame they have no direction so the points just take their current heights so they can use them for comparison on the second and every other frame int temporary_Direction; float temporary_Previous_Frame_Height; if(@Frame == 1) { temporary_Direction = -1; temporary_Previous_Frame_Height = @P.y; } else { temporary_Direction = @Direction; // ------------> this is where the problem is (this is here so that the temporary variable get's the value of the currently proccesing point every frame) temporary_Previous_Frame_Height = @P.y; if(temporary_Direction == -1) // If the point has no direction { if(temporary_Previous_Frame_Height < v@P.y) // If it's going up { temporary_Direction = 1; temporary_Previous_Frame_Height = v@P.y; } if(temporary_Previous_Frame_Height > v@P.y) // If it's going down { temporary_Direction = 0; temporary_Previous_Frame_Height = v@P.y; } } } // Out_Values i@Direction = temporary_Direction; f@Previous_Frame_Height = temporary_Previous_Frame_Height; // Out_Values The problem here seems to be when I declare "temporary_Direction = @Direction", for some reason on the second frame when I read @Direction the value wich is given to temporary_Direction is 0 instead of -1 wich was given to every @Direction on the first frame. Temporary_Previous_Frame_Height updates just fine but temporary_Direction doesnt. Also writing "if(temporary_Direction == -1)" doesnt seem to work either. Is my thought process even slightly right here, what am i doing wrong, are temporary variables created in vex something that exist globally and in order to use them per point we need to read each point's values or are temporary variables something that exist for every point. Also why do i have to give values to all attributes every single frame or else they will reset to 0 (hense the Out_Values section). //////////////////////////// Update Thank you everyone for replying. I've tried out the time shift sop and it work's fine now( I dont even need the Previous_Frame_Height attribute anymore). I've updated the main post with the original hip file and the one with the time shift sop. Learning about the time shift sop is great, but i would still like to improve my thought process on writing code. It would be greatly appritiated if someone can take a look at the original hip file and possibly shed some light on the problem. I've added notes inside the original hip file for clarity. Any help would be appritiated Thanks in advance Original.hip Time-Shift SOP.hip
  14. hey guys i'm trying to do a basic FEM test here and having a prob with attributes I paint up an attribute call 'shapestiffness' then i'm trying to pass that to dops - so i've entered @shapestiffness into the slot in the solid object node in my dop network. My understanding is that the attribute should act as a multiplier but i cant get it to work it just splats on the floor this is probably comically easy for some of you but i'm still trying to wrap my head around attributes to control objects and stuff so bear with me I've attached a super simple ball scene where you can prob see what i'm failing to do lol! anyone got a few mins to take a quick look? ta ant shapestiffness_variable_FEM_test01.hip
  15. Like the title says. I'm trying to kind of make my way through the SHOP context, but my biggest problem is accessing information from the actual geo. I made a fairly simple scene where I am running a sin over the sphere's @pscale. In this case I'm just trying to have the @pscale control the principal shader's emission amount. I tried making an attribute VOP where I bind the @pscale to a bind export and then named it "lit". After this point I can't fin an answer online how to access and connect that attribute to the emission. I know it has to be the easiest and most obvious node, but I can't seem to find the answer. All help is much appreciated! size_lit.hipnc
  16. What is the difference between creating the name attribute in the voronoi fracture, or later in the assemble?
  17. FumeFX VDB in Houdini?

    So I come from a Max background using Vray. I can load in VDB's from Houdini through Vray's VolumeGrid. I was trying to do the reverse; load in FumeFx VDB's into Houdini. I can load in the VDB's no problem and I see it in the viewport. However, trying to use the volume shader is entirely different. When I click the VDB in the viewport and go to the primitives view I can see Fume's channels. I'm not sure it's even possible but I attached a screenshot to better explain what I'm talking about. I would attach a .VDB file but it's 100mb so...But the scene is literally loading in the file and then has a transform to scale it down. Thanks!!!
  18. Student Demo Reel

    Back in January I didn't know Houdini existed until I started school and ever since I've been trying to learn as much as I can. I still have a lot of work to do and there is a lot more I want to learn/try but this is all I've learned up until now.
  19. Tron Derez Effect

    Took me a while to get this far on this project. But I managed to somewhat recreate the derez effect from Tron: Legacy.
  20. Attributes in Houdini Tutorial

    Hello friends, yet another explanation of attributes in Houdini. Hope you will find it useful ))
  21. Hi everyone, The new GridMarkets Houdini artist feature is out! Johnny Farmfield, Houdini artist from Sweden, shows us how working with attributes is key to understanding the Houdini workflow. Don't miss his entertaining and extensive tutorial. Have a great week, Patricia and the GridMarkets team
  22. Hi all, Am trying to tweak a scene file that was passed to me from here (apologies, I don't know/can't find original poster, so can't credit). It's a wire sim where points are activated based on their Y position - And I'm trying to tweak it to be based on color. I've worked a nice way to animate my colour across the points in a way I like, but my question is: How do i get my point color attrib to update per frame in the dopnet? And how do i associate it to the gluetoanimation value? Been really trying to get this going today, but to no avail... Any help or tips gratefully received! activate_sim_based_on_color.hip
  23. Hi everyone, I apologize if this has already been asked but i couldn't find an answer for this precise case. I have points with a bunch of attributes and I'm using an Instance Node to render them. Each instances is set by an instancefile attribute. I want to use the id attributes to export aovs from the shader but I can't find a way to have the instances inheriting the points attributes. You can see in the example file what I wish to do with the instance display node unpacked. I saw post about the function instancepoint() applied to the object to instance but I guess that in my case I cannot use this with instancefile since files are written ahead. Maybe should I find an other way to instance my geometries which are currently in files debris.0001-0050.bgeo.sc using the attributes pieceNbToInstance to somehow filter the piece to import but ideally I'd like to use the easiest way if possible so I don't write unneeded stuff in the IFds. Any ideas ? Thanks ! Chris instancefileWithAovsUsingAttributes.v1.hipnc
  24. polyExtrude Unfamiliar options

    How do I add an input curve to the polyExtrude which is outside of the current context ? Can someone correct me if I'm wrong, from my understanding of the splitGroup option within the polyExtrude is suppose to add edge splits to the selected geometry ? I have the option toggled on in the polyExtrude node, along with a group selected but I don't see any edge splits ? Local attributes, all the manual states is, for example, for distance scale is; Multiply the extrusion distance by the value of this attribute ?
  25. VDB maintain UVs

    Hello All, I am using VDBs to combine geometry and I am interested in a way of maintaining specific attributes from the two input geometries. Currently I have two poly objects which are being converted to VDBs and then combined using VDB combine and then converted back to polys using VDB convert. What I want is to be able to identify which polygons on the resulting combined/converted object comes from which input object and also maintain their respective UVs. I have had some success with using the second input of the convertVDB node to transfer attributes. Using this method however, I am only able to maintain some of the objects attributes, not all. I've attached some images and a file to demonstrate my issue. In the attached file I have three objects; Base, Add Sphere and Sub Sphere. All objects contain UVs and an ID attribute (tmp1), they are all converted to VDBs then combined using VDBcombine nodes. Finally the resulting VDB is converted to polys using convertVDB. When both original sphere are input into the second input, the UVs and ID attributes are transferred correctly however the Base object is not. When all three objects are input into the second input of the convertVDB, only the Base and one sphere's attributes are transferred correctly. I have tried several different combinations and methods of making this work to no avail, but it feels like I'm so close if I can get all three objects to transfer the attributes correctly, just not all at the same time. It is possible to use two convertVDB nodes, one with the two spheres in the second input and the second with all three objects in the second input, then deleting the problem polys from either (using the ID attribute) and then merging the two together, but this is not very ideal. In the image on the left you can see the results of the convertVDB using only the two spheres as the second input, the middle image is when using all three objects (base, add_sphere and sub_sphere), and the right is an image of all three input objects showing their UVs. I am new to VDBs so I was hoping someone might have some alternative methods or could point me in the right direction. Thank you all in advance! Cheers, -Mat VDB_attributes.hip
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